Dart vs AFR heads on HP 500
 

Just purchased boat and am Looking at two different types of heads for a pair of hp 500's with 450 hrs, any comments on the dart pro-1 310 or the AFR 315 heads, which one would yield the best set up to have a solid 600 hp on stock 500 hp's ? trying to achieve a solid 85 mph on a 34 vyper. Boat has had some top end work done but has stock heads and the hours indicate a top end rebuild anyway so i figure i would change out the top end except the intake and carb, I.E cam lifters rockers and heads. Allready has EMI-512 manifolds with silent choice. Thinking of this route since i got a lot of feedback against the supercharger way.

Re: Dart vs AFR heads on HP 500
 

The afr315 heads out flow the dart 310's by 10% on the intake and 20% on the exhaust,more importantly they have a nice intake to exhaust ratio of around 75%.You would have to spend big bucks on professional porting to get the darts to match and even then they still might not. For more info check out the headflow data base:http://users.erols.com/srweiss/tablehdc.htm#BBChevy
Rmbuilder (aka bob madera) is a dealer for afr heads and can get you the best pricing and has good availability on the afr's,you can reach him at 585-654-8583. He has also profiled cams that work VERY well on motors with afr heads that will still idle good and have a REAl marine power band with torque and hp where you can actually use it,Smitty

Re: Dart vs AFR heads on HP 500
 

I prefer naturally aspirated engines too and they're a little easier to detect when something starts going wrong vs supercharged engines---they definately make power, but have more moving parts, require more maintenance, more stress on parts, and they're prone to breaking drives a little easier.

Are you looking at both Dart and AFR in the CNC'd mode? I have had both heads...first the non-ported Dart 310's, but then had JimV fully port them. Then a few years later I bought some AFR 315, cnc ported heads which I now have on my 565cid naturally aspirated engines.

About a week ago I was by myself out on Lake Michigan in my boat testing some new props and ran into a friend of mine who owns a 32' Active Thunder just like mine---same hull. He has a pair of 557cid super charged engines with Dart Pro-1 heads (don't know what size) that supposedly make 810hp on the dyno vs my little naturally apirated 565cid wimp engines that don't make any power. I have even seen the dyno sheets of his engines built by Ultra Tech in Indiana.

Anyway, I guess he suddenly decided he wanted to go to guns with me, so we got it on and he could not pull me in acceleration (from about 3500rpm) and once we got up to the top he couldn't pull me there either! There ARE variables, but neither of us was able to out do the other, but as close as we are in cubic inches for the least dollar$ spent, and the speed he is running I am sure he is the winner there! He mentioned to me he's gonna pull the engines and have bigger cams installed---it never ends! :crazy: None the less, I think he was a little surprised I could hang right there with him and I'm very pleased with how my little hog runs.

I guess what is really surprising is when a bass fishing boat, or the Sea Doos the have these days comes by you at speed---now THAT is painful!!! :snide: Anyway, have fun with your project.

Re: Dart vs AFR heads on HP 500
 

Kaama,
Didn't you have some flow data you posted before on OSO for your Pro1's before/after Jim finished with them. It would be interesting to see that.

Rick

Re: Dart vs AFR heads on HP 500
 

Dart and AFR make some killer heads...no doubt.

Either would be a terrific choice.

Do we go with Tony or Richard ? Hmmmm. As a human I'm partial, and in an application like this I'm a little more partial to AFR.

Re: Dart vs AFR heads on HP 500
 

do any of you guys have an opinion on, or have tried the eldelbrock rpm aluminum heads, i saw them in a summitt racing catalog and they have a" marine" version with hardened valves and anti corrosive coating. i also have an hp500 i was considering porting the stock iron heads or going aluminum, just trying to research where to spend the $ for best results

Re: Dart vs AFR heads on HP 500
 

Okay yall, here are some flow number comparisons as RV has requested I post. JimV fully ported the Darts Pro-1's 310's and installed some larger 2.30" intake valves---this also included one of JimV's chamber port jobs which provides even more power. The AFR 315's were CNC ported with a smaller 2.25" intake valve. Flow numbers are from JimV's Super 600 Flo Bench @28" of water. WITHOUT 6" pipe.

Dart 310cc Pro-1with 2.30" intk valve
Intk Ext
.2 149 130
.3 225 171
.4 295 206
.5 348 256
.6 380 286
1397 1049 (total cfm)

AFR 315cc as is out of the box with 2.25" intk valve and best flowing Ferrea exhaust valve that you can get from AFR with this head
Intk Ext
.2 164 140
.3 243 193
.4 306 232
.5 357 250
.6 380 254
1421 1069 (total cfm)

We wanted to improve the flow numbers from .500"-.600" lift on the exhaust side of the AFR's-----so, I gave JimV the nod and he went in and did a little hand massaging of the exhaust ports so, here's what we got...

AFR 315 w/JimV exhaust port hand massage WITHOUT 6" pipe!
.2 146
.3 201
.4 246
.5 268
.6 279
1141 (total cfm)

Okay, we all know that AFR advertises their exhaust flow numbers WITH a 6" PIPE! So, I have listed results below...

AFR 315cc JimV exhaust mods WITH 6" pipe
.2 146
.3 213
.4 263
.5 290
.6 320
1232 (total cfm)

My cams have a lift that sits somewhere between .600" and .650" lift and the flow numbers on the AFR exhaust port with JimV mods and a 6" pipe is 327cfm.

So you can see the AFR's didn't quite flow as they are advertised out of the box...but I am sure air density and barometric pressure, etc, etc, may have something to do with that...not sure. However, you can see that the AFR 315's still out flowed the Dart 310 Pro-1's...even with larger intk valves and one of JimV's chamber port jobs. Then the AFR's got even better on the exhaust side with JimV's massaging. Now that's the last time I am gonna splain it to yall! :D

Re: Dart vs AFR heads on HP 500
 

Kaama,how did the exhaust ports flow BEFORE the porting with a extension tube on them? Smitty

Re: Dart vs AFR heads on HP 500
 

I am a proud owner of two sets of 305 cc AFR's with cnc'd chambers.
They are on my HP 500 carb motors in a 382 Fastech. The only parts that are not original HP 500 are the heads, custom cams, lifters and push rods.
These motors made 620 HP @ 5500 rpm and have a strong Idle.
This is with the original 800 cfm Holley's and gil exhaust.
I have 280 hrs on these motors with no problems. The boat picked up a solid 8 mph on the top end with this upgrade, now running 82 mph.
As smitty said call Rmbuilder (aka bob madera) for all your valve train and afr's, He knows marine engines and how to get a 600+ HP 502.
Jeff

Re: Dart vs AFR heads on HP 500
 

Here you go Smitty...

AFR 315cc (as is) out of the box WITH 6" pipe on JimV's flow bench

.2 146
.3 206
.4 251
.5 280
.6 287
1170 (total cfm)

So, there looks to be a 62cfm difference between out of the box vs the same port with the JimV mods.

Also, at .650" lift it is 291cfm

Re: Dart vs AFR heads on HP 500
 

Boy let me tell ya all you guys are great, this is got to be the best forum i have seen yet, no BS and right to the meat of things. I will call RM to fine tune my project to achieve 600 hp on 500's, so far it looks like a soild build up would be the 315 full cnc AFR heads along with crane cams # 139741 or what rm would suggest, as well as roller lifters and rockers, along with the eddie marine 512's. I am hoping for a solid 85 mph set-up with this in mind. Once again thank you all for your input.

Re: Dart vs AFR heads on HP 500
 

As you can see, the AFR CNC'd exhaust ports the way they come from the factory are 20cfm better than the Dart Pro-1 exhaust port as ported by JimV-----------and with the JimV exhaust mods the AFR is 92cfm over the Dart.

Laszo, Bob Madara/"RMbuilder" can set you up with the AFR heads and a cam app as he has done for me and several others. Glad you liked the info.

Re: Dart vs AFR heads on HP 500
 

Lazlo - Wags combo should the one your interested in. 1st reason why - started from same engine. #2 - the exhausts are very similar.

8mph from a LARGE 382 Fastech is terrific from a cam + head change.

This build always impresses me from a cost, engineeering, and results produced standpoint.

Re: Dart vs AFR heads on HP 500
 

Oops - just read you have silent choice. This forces the water to be introduced way earlier in your exhaust. This may cause issues. Talk to Bob (rm) before you finalize any choices.

Re: Dart vs AFR heads on HP 500
 

Condor,

JimV has ported some of the Edelbrock aluminum heads for a guy in the Detroit area I believe about a year ago. Before JimV touched them they weren't that great out of the box. If you're going to buy new aluminum heads, then buy some of the better ones like the Dart, Brodix or better yet, the AFR's all with cnc'd porting. JimV was able to improve the flow on Edelbrock's, but even then I am not sure if he was able to still get close to the same kind of flow numbers that the other BIG name aftermarket head manufacturer's make. If you are going to buy new aluminum, then buy a better casting if you can. Otherwise, JimV can probably improve the flow on just about any head you have.

Re: Dart vs AFR heads on HP 500
 

what about alum vs iron?
i hear afr is great, but i just replaced a set of alum heads which broke due to salt water for dart irons for long life. whats the life like on afr heads even after you flush them after every salt water use?

i would love to build a set of spares with afr heads but if they only last 8 yrs u think that would be a waste if the pwr gain is not to mch greater over dart? so far i love the darts!

Re: Dart vs AFR heads on HP 500
 

Kaama,
Thanks for posting that, I new you could dig that up!

Rick

Re: Dart vs AFR heads on HP 500
 

Kaama - that is true about the Edelbrock's. Yes, they are a decent head, but there are much better one's. I've talked to many head porting Guru's and they say that there are some design traits that you just can't ultimately get around when porting.

Others will instantly say - heh, Edelbrock makes the GMPP heads and Mercruiser's 525EFI heads so they are the same. I'd like to tell/remind people that THEY ARE NOT THE SAME. Don't fall victim to that assumption.

Re: Dart vs AFR heads on HP 500
 

I am curious to know what brand of aluminum heads you had failed with the salt water. Have you heard of the "hard anodized" that some of the head manufacturer's offer as an option on the their aluminum heads to keep or help keep them from corrosion? When I had RMbuilder order my AFR's we ordered them with the hard anodizing, but I honestly don't know how well they have held up on anyone elses boat in salt water....maybe if they see this they can chime in and let us know.

Re: Dart vs AFR heads on HP 500
 

i was running edelbrock heads. i dont believe they where anodized @ all. i think they where prob a jegs cat order, and where on the boat when i bought it. that is great to know, b/c seems like all are suggesting that afrs flow well

Re: Dart vs AFR heads on HP 500
 

Here's a couple shots of my AFR's with the hard anodizing (black coating) on the stands as my engines were being assembled about a year ago. I thought the quality of how the hard anodizing was applied to the heads that AFR did looked so good that I decided not to paint them and leave them as they came...

Re: Dart vs AFR heads on HP 500
 

Kaama,
From your picture it appears that you have a different way of routing the water flow through your engine. Do you have any pictures showing it completed. I am interested in how you plumbed the water flow. Looks like you have one of those thermostat housings from Rex with the bypass valve/spring. Is that true, if so how has that worked out for you. I am thinking of using them on my engine. Currently running a crossover w/o thermostat and would like to build some heat w/o excessive water pressure.

Rick

Re: Dart vs AFR heads on HP 500
 

For this build, you will should consider an ignition upgrade as well. I have the same combo AFR 315, Crane 168741, 1.7 rockers on the exhaust and 1.8 on the intake, Stock 6200 Dart Intake and Holley Stock 800, HVH 1" Super Sucker carb spacer, CMI Elbow Tops...around 630hp. Look at the Crane Hi 6M ignition box(6000-6462) and LX92 coil (730-0892).

Dave

Re: Dart vs AFR heads on HP 500
 

Hi Mark, they look good in flat black. Your flow numbers are almost identical to mine even though I went to the AFR 335's. Mine average 290 ex. at .6 lift though. :D One of these days I'm going to build a pair of 632's and put these heads on them. I'm sure they flow well enough to support that many cubic inches at 5500 rpm's. Ian

Re: Dart vs AFR heads on HP 500
 

632 " ? I'd go Raptor 12 degree oval ports. LOL!!! freakin' expensive but a whole lot of fun 'oh schit' !!!

Just playin/dreamin/joking.... kind of.

[img] http://www.rehermorrison.com/images/Raptor-web-ad.jpg [/img]

Re: Dart vs AFR heads on HP 500
 

I find it interesting that AFR seems to do the machining after the hard anodizing.

On the Canfield heads, the anodizing is done after the machining (even after combustion chamber work and etc if you opt for that) - no exposed aluminum.

I'm no chemist or metallurgist. What's everyone's thoughts on the two methods ? Longevity ?

Re: Dart vs AFR heads on HP 500
 

Wow, those are cool! But how would they work in a recreational boating enviornment? And $$$$$. Maybe someday on an all out poker run boat.

Re: Dart vs AFR heads on HP 500
 

Ian,

Glad you posted. Just so that everyone knows---the EXHAUST port on AFR's 305, 315, 335, and 357cc heads are ALL THE EXACT SAME PORT!!! JimV enlarged your exhaust port size more than what he did on mine because I told him that I wanted him to try and maintain the strong mid lift numbers as much as I could without sacrificing them too much for the bigger flow numbers at .600" lift. I told him to try and do that without increasing the diameter of the port too much if he could so, that's why mine might be slightly lower flow numbers than yours. That just shows the potential of the AFR's and that JimV can get even MORE FLOW from the AFR's if the customer wants to such as in your case---which is a great thing!

Re: Dart vs AFR heads on HP 500
 

RV/Rick,

Probably the best way to show it is with the engines plumbed the way I run it in the boat. Until then this isn't too bad of a shot, but as you can see I use a CAM DRIVEN water pump which some people do not like because they don't seem to pump enough water at idle speeds. I have found this to be somewhat true...as the headers run a little warmer, but the engines still run fine with a 120* thermostat. I run about 18-22 pounds of water pressure while on plane and have no need of any high pressure relief valves. So far it is working well for me.

Maybe I can get a bit of a better/closer shot for you this weekend.

Re: Dart vs AFR heads on HP 500
 

who has the best pricing on the AFR 315

Re: Dart vs AFR heads on HP 500
 

Are the Edelbrock heads the only alumn. heads with the exhaust port in the same location? I think that the AFR and Dart both have raised ports which could be a problem as far as clearence is concerned.

Re: Dart vs AFR heads on HP 500
 

Brodix Race Rite's have standard intake + exh locations.

Good #'s for standard layoutr heads. Available out of box with 270cc Oval port or 294cc Rect port. Avaliable with a CNC combustion chamber that up's the flow even more.

Won't compete with a raised runner intake + exhaust port though.

Always check on the exhaust ports...some raised one's are near .300" and some go all the way up to .625" or so.

Ex manifold applications usually don't have much a problem since they use a good length of rubber tube to the tailpipes. Most tubular headers and some manifolds with real long risers will have issues.

Re: Dart vs AFR heads on HP 500
 

Kaama,
Thanks for the completed picture. That is good enough for me, you do not need to take any more. I have a couple follow-up questions:
1. Does that thermostat housing have the valve with the spring that acts as a bypass while the thermostat is closed and then closes the bypass once the thermostat opens?
2. Are the hoses to/from thermostat housing #12's?
3. Are the AN hose adapters 12AN to 1/2 NPT or 3/4 NPT.
4. Is the 18-22#'s of pressure at WOT or cruise?

Sounds like your setup is dialed in.
I also see you are using large tube full lenght headers. Did you have any insight on how your setup would do with elbow tops w/ 1 7/8" standard runner tubes?

Thanks,
Rick

Re: Dart vs AFR heads on HP 500
 

I have had the good fortune to be able to witness firsthand the performance of many of the boats owned by posters on this thread. One common trait of all these AFR headed engines is the application of power throughout the RPM range. This is due to the high flow numbers (low/mid/high lift) combined with a relatively small CSA. Not only are you moving significant quantities of air, you are doing so with very high port velocities. High peak flow numbers mean little without the column energy needed for proper cylinder fill. Without the proper port velocity and CSA, more energy is wasted initiating column motion and less inertia is present at IVO.

One factor less talked about is the combustion chamber program. These heads seem to always turn very good BSFC numbers, which is a strong indicator of chamber efficiency.
I plotted some BSFC/Torque graphs showing the fuel numbers relative to the torque output and in each case the curves are virtually inverse overlay, with lowest BSFC (.39-.41) occurring +/- 100 RPM of peak TQ (max VE).

Re: Dart vs AFR heads on HP 500
 

See, I told you Bob knows his $hit.
The 305 cc Afr's and a small cam are all you need to achieve that 620 HP with your 502.
The "741" cam does not have the proper ratio from intake to exhaust duration and has more duration than you need, pushing that torque too far up the rpm range.
Jeff

Re: Dart vs AFR heads on HP 500
 

I have had good luck and decent power with my NA 540 running AFR 315 CNC heads. Here are pictures of the ports as they came from AFR.

Re: Dart vs AFR heads on HP 500
 

I run the AFR305s with custom cams from RMBuilder. Most people get the anodized option with the CNC port option. Bob (RMBuilder) knows his stuff. Got 605 hp at 5500 rpm on the dyno. I installed Crane HI6M modules with adjustable rev limiters to increase rpm range. My 32 AT runs 85 to 87 (added 6 to 7 mph) GPS depending on weather/load. Boat accelerates like a blower boat due to the high torque produced throughout the power band. Great idle. Call Bob Madera.

call me for more info

3375408228

Tom

Re: Dart vs AFR heads on HP 500
 

i changed out the stock hp500 cam in my motor for the crane "731" which AFR head combo would give me the best results ?, running lightning headers and nickerson holley carb.Also are my springs,guides and rockers applicable from my iron heads to the aluminum ones or do i need to purchase new stuff (sorry for my limited knowledge on this topic :p )

Re: Dart vs AFR heads on HP 500
 

I cannot recall the the Crane 731 cam specs, but it might have too long of a intake/exhaust duration split for it to work well with the AFR heads. The head/cam combination have to work together for the engine to produce good results. I'm not saying a 731 cam wont still work, but you might as well retain the stock cast iron GM heads you now have and have some pocket port/bowl work done to them if you are going to keep that cam. With too much of an I/E split on the cam you'd still see some power increases with the AFR's, but without a properly selected cam you will be holding back their potential by not letting them do their job correctly.

Also, anything new would be good idea, although you can probably re-use the rocker arms you now have---just inspect them, but you may need a different length rocker arm stud for the AFR heads. I would highly suggest new springs, retainers, lifters, and pushrods. RMbuilder would be excellent to consult for your cam/valve train and will work with you & your engine builder.

Just make sure that whoever is doing the work does the job RIGHT and KNOWS what the heck he is doing...not by his sweet talking words---but by someone who has a lot of experience and a good reputation because there is a lot of $$$ involved and there won't be much room for error.

Re: Dart vs AFR heads on HP 500
 

Rockers will work. Pushrod length is different,you will need custom length pusrods. Get .080 wall thickness Comp 1 piece pushrods. Unless the springs are almost new, now would be a good time to get new ones.